The present invention relates to an apparatus and a method for activating a binder substance on a fiber preform which contains carbon fibers. Activation of the binder stabilizes and sets the fiber preform; a component made of carbon fiber reinforced composites can then be produced from a fiber preform. In what follows, a semi-finished fiber material is understood to mean a fiber package which does not yet exhibit the shape of the component, has not yet undergone the forming process, or is still unformed. A fiber preform is understood to mean a fiber package which already possesses the shape of the component, or which has been fully formed. The fiber preform has not necessarily been stabilized and set.
Components today made of carbon fiber reinforced composites are produced from pre-impregnated semi-finished materials, prepregs, or from dry semi-finished fiber materials which are then impregnated with resin. If dry semi-finished fiber materials are used, a fiber pre-form is usually produced first from these semi-finished fiber materials; this is a dry fiber package which already anticipates the later shape of the component. Today, the dry semi-finished fiber materials or the cloth pre-products, for example wovens or multiaxial reinforcements, are assembled and then brought to the desired shape by reorienting and reshaping (draping) the arrangement of the fibers. A woven, for instance, is a fabric produced on a loom composed of two orthogonal filament systems (weft and warp); a multiaxial reinforcement consists of several layers of fiber which are laid on top of each other in different directions and are stitch bonded using thin threads. A binder system may be used to assist in setting the preforms. The binder systems in use are mostly thermosetting or thermoplastic substances which may be in powdered form, are used in a relatively small quantity, in the range of 2 to 5 percent by weight for instance, are applied to the semi-finished material and activated under the effects of heat or by increasing the temperature. In addition to establishing the fiber orientation, the binder systems can be used to set the preforms in a more compacted state. Setting the preform effects a punctiform, loose set of the fiber laminate, or of its shape, more or less an initial setting. A preform set in this way can then be stacked and warehoused prior to further processing. The final fiber-composite laminate, or the final component, is then produced by saturating the set preform with a relatively large volume of a matrix (between 25 and 85 percent by volume relative to the component, for instance,) and by subsequent curing of the matrix component, or by allowing it to harden.
In the case of the prior art methods of setting the preform, the binder is usually activated by heating the preform, for example with the aid of an infra-red heater or hot air (in an oven for instance, or with a hot air gun). A serious disadvantage of these prior art methods is that they can only heat the preform very slowly over the entire material thickness since the energy transfer is not very high and the preform tooling, described in what follows as the preform shaping apparatus, is also heated up and the tooling or the apparatus must then be cooled down again in a long cool-off phase. For this reason, the cycle times in preform production in the prior art are relatively long.